The overall objectives of this proposal are to identify gene products that determine the specialized morphology of a cell and to study the control of their cellular localization. The sperm of the nematode C. elegans is chosen as the cell for study because sperm have specialized surface morphology, because many mutants altering morphology can be obtained by screening for their sterile phenotype, and because the sperm can be isolated for biochemical characterization. Seven genes that can mutate to cause defective sperm have already been identified. The sperm in males mutant in three of these genes are defective in the fusion of an internal membranous organelle with the plasma membrane. One of these mutants is also altered in sperm phospholipid composition. Another gene causes accumulation of large tubular elements in the sperm cytoplasm. We propose to continue to characterize the sperm morphology of these and additional mutants with scanning electron microscopy and transmission electron microscopy of both thin sections and freeze-fracture replicas. In parallel mutant sperm will be analyzed for alterations in membrane and cytoplasmic proteins by gel electrophoresis and for alterations in membrane lipids. They will also be characterized immunologically using absorbed anti-sperm antisera and monoclonal anti-sperm antibodies. By correlating the biochemical and immunological analysis of mutants with their morphological alterations the normal role of the mutated gene products in determining cell morphology will be deduced and possible mechanisms for localization will be tested.